against
24 in 1911 and 16 in 1910. The daily average capacity of the dredges in
1912 was 1,000 cubic yards, and the average approximate recovery varied
from 52 to 64 cents per cubic yard.
The
total gold production from gold-lode mines in Alaska since 1882 is
estimated at $57,811,300, and the total placer output of Alaska for the
same period is estimated at $154,800,848.
It
is estimated that there were 720 placer mines operating in Alaska in
1912 against 740 in 1911, and that 6,300,000 cubic yards of gravel were
washed in all, by various methods, with an average recovery of $1.87
per cubic yard, against 5,790,000 cubic yards in 1911, with an average
recovery of $2.17 per yard.
Silver.—The
production of silver in Alaska in 1912 was 515,186 fine ounces against
460,231 ounces in 1911. Of the total production, 376,593 ounces were
obtained from copper ores, 102,897 ounces from gold placers, and 35,696
ounces from the siliceous ores of the lode-gold mines.
It
is estimated that the total silver production of Alaska since 1882 from
auriferous lode mines has been 1,065,439 ounces, and that the total
silver recovery from placer gold has been 1,652,016 ounces.
ARIZONA.
Gold.—The
gold production of Arizona in 1912 was $3,762,210 against $3,430,503 in
1911 and $3,149,366 in 1910. This was again the largest gold output in
the State in recent years, and, as in 1911, the increase was again
mainly due to greater production from the gold milling ores of Mohave
County and from the copper ores of Cochise County. In output of gold in
Arizona Mohave County again led, producing $1,899,131, or half the
State total in 1912, against $1,547,663 in 1911. The production is
chiefly from the siliceous gold ores of the Gold Koad and Tom Reed
mines m the San Francisco district. Cochise County again ranked
second, with its largest output from the copper ores of the Warren
(Bisbee) district. Yavapai County also made an important output from
copper ores of the Verde district, and Maricopa a considerable
production from the Vulture district. By the amalgamation process
$236,345 in gold was produced in Arizona in 1912, and $1,877,241 by
cyanidation. Crude ores shipped to smelters contained $1,386,809 of the
gold output, and concentrates shipped contained $212,434. Placers in
Maricopa, Mohave, Pima, Pinal, Yavapai, and Yuma counties produced
$43,046 in 1912, against $23,641 in 1911.
Silver.—The
output of silver in Arizona was 3,490,387 fine ounces against 3,276,571
ounces in 1911 and 2,566,528 ounces in 1910. Cochise County alone, and
principally from copper ores of the Warren district but also from lead
ores of the Tombstone and other districts, produced 1,962,644 ounces
in 1912 against 1,946,319 ounces in 1911. Yavapai County again ranked
second in output with 748,872 ounces in 1912 against 764,744 ounces in
1911, mainly from copper ores of the Verde district. Gila County ranked
third, with 264,941 ounces in 1912 against 247,813 ounces in 1911,
mainly from the copper ores of Globe. Mohave County produced 174,343
ounces in 1912, about half of which came from zinc ores, and Pinal
County, 109,686 ounces, almost entirely from copper ores. Of the total
silver production of Arizona in 1912, copper ores supplied 2,378,593
ounces;
